Lecture 9 2/12/24 Flashcards
What are the general characteristics of neg. strand RNA viruses?
-genome is complementary to mRNA
-cannot be directly translated by host cells
-RdRp required to transcribe neg-sense RNA into pos-sense RNA before protein synthesis
What are the characteristics of vesicular stomatitis virus?
-neg. ssRNA genome
-bullet-shaped
-enveloped
-helical symmetry
-Rhabdoviridae fam.
-easily manipulated and used to study other viruses
What happens when the VSV genome is transcribed into + sense RNA and used to produce mRNA?
the mRNA is made up of a bunch of small fragments that each encode a viral protein
What are the characteristics of influenza virus?
-Orthomyxoviridae family
-enveloped
-eight segments of (-)ssRNA
-two major surface proteins, HA and NA
What are the four types of influenza viruses?
-A: humans, birds, pigs, horses, mammals
-B: humans, aquatic mammals
-C: humans, pigs
-D: cattle, pigs
What determines the species that each influenza virus will infect?
the type of sialic acid that the virus binds to
Which type of sialic acid does influenza bind to in humans?
alpha-2,6
Which type of sialic acid does influenza bind to in avian species?
alpha-2,3
How does influenza begin its replication process?
cap snatching
What is antigenic shift?
-when two influenza viruses infect same host cell and exchange genetic material
-creates a new strain with different genetic makeup
What is antigenic drift?
-occurs when mutations arise in influenza genome over time
-small changes in viral genetic makeup
Which other neg. ssRNA viruses are of importance?
-paramyxoviruses
-bunyaviruses
What are the characteristics of reoviruses?
-dsRNA genome
-non-enveloped
-capsid structures with two layers
Which animal viruses are reoviruses?
-avian orthoreovirus
-bluetongue virus
-African horse sickness virus
Why can reoviruses not immediately produce mRNA?
the pos. sense strand is not accessible to ribosomes due to the double stranded structure
